|Production Know How
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The Angoumois grain moth is the most serious pest injurious to rice, both in the field and storage.
This moth also attacks other cereals like maize, wheat and sorghum.
The infestation may reach serious levels before the grains are transported to the storage godowns resulting in around 25 per cent loss in weight and seed viability.
The larva is an internal borer of the whole grain, feeding on the starchy part. Severely infested material emits an unpleasant smell and looks unhealthy in appearance.
Grains are often covered with scales shed by the moths. The grains are practically hollow and filled with larval excreta and other refuse making it unfit for consumption.
The adult is a small, straw coloured moth. The female can lay an average of 150 eggs on unhusked paddy grains.
They hatch in a week’s period. Newly hatched caterpillar is yellowish white in colour with a brown head capsule. It soon bores into the grain and feeds on its contents.
Larval stage lasts for about three weeks. Before pupation, the larva constructs a silken cocoon in the cavity made during feeding and turns into reddish brown pupa.
After a period of 4-7 days, the adult emerges. Entire life cycle is completed in 30-35 days.
Several generations are completed in a year. Adults are short-lived and can be seen flying about in large numbers in storage bags and on the surface of grains.
— Drying the grains under sun for three days to reduce moisture content below 12 per cent is suggested.
— The jute bags to be used for storing grains have to be dipped in insecticidal solution of fenitrothion 50EC at 5ml/20 liters of water.
— Application of dichlorvos (DDVP) 76SC is recommended on the surface of stored jute bags by dissolving 7ml/lit. of water and the spray solution is sprayed at three lit/100 sq.m.
Pink stem borer (PSB), Sesamia inferens (Walker)
Distribution: This species has been reported from all over India but is more common in areas where rice is followed by wheat crop and also in upland rice regions. Description: Adult are whitish to dark straw coloured with white hind wings. Sexual dimorphism is conspicuous. The male moth is slightly smaller than the female and has pectinate antenna. The female has filiform antennae. Larva is purplish pink dorsally and white in colour ventrally with an orange red head capsule. Biology: Female moth lays more than 400 eggs in batches of up to 161 eggs. They are laid between leaf sheath and stem in rows of 2-3 or on soil surface near base of the plant. They are creamy white to dark and naked. Egg period varies with season, 4-9 days in summer and 9-25 days in winter. The caterpillars do not tend to congregate but disperse early. Larval duration is for 3-4 weeks with 5-7 moults. Pupation usually takes place inside the larval tunnel within the stem and pupal period varies from 5-12 days in summer and 12-36 days in winter.
Host plants: Maize and sugarcane are the cultivated hosts apart from 33 other species being reported as alternate hosts.
Gold fringed borer (GFB), Chilo auricilius (Dudgeon)
Distribution: This is an important pest of sugarcane and rice. The distribution range of C. auricilius overlaps with that of its look-alike C. polychrysus. It is also found in West Bengal, Bihar, UP, Gujarat, Jammu & Kashmir. Description: The adults resemble the adults of C polychrysus and can be distinctly differentiated by their genitalia and larvae by thoracic chaetotaxy. The forewings are 8-13 mm long, with yellow or occasionally brown colour, and are variably ornamented with brown scales. A discal spot is present and there are rows of sub-terminal and median metallic scales. There are also a few small silvery specks in the middle of the wing, the terminal dots are large and the fringe is shiny gold. Coloration and pattern of silver specks on forewing is variable. In some cases the forewings are uniformly yellow. The hindwings are light brown. The silvery specks are sometimes irregularly dispersed, while in other specimens they form two parallel transverse lines. First-instar larvae are about 1 mm long and creamy-white, with a black, dorso-ventrally flattened head. A full grown larva is cream to dull in colour; head dark fuscous, body with 5 violet stripes. The crochets on the abdominal prolegs form a complete circle. Biology: Eggs are laid on the under surface of the rice plants and at times also on the leaf sheaths. The oviposition period is 3 days and nearly 123 eggs are laid per female. The eggs hatch in 5-7 days. The larval period varies from 30- 32 days undergoing six moults. The pupal period is for 6 days. The postero- lateral and postero -dorsal spines on cremaster of pupae are more prominent. There are 5-7 generations in India.
Dark headed borer (DHB), Chilo poly chrysus(Meyrick)
Distribution: It has been reported from Kerala, Assam, West Bengal, Orissa and Tamil Nadu but it often assumes the status of major pest in Tamil Nadu and Kerala. Description: The forewing is brownish ochreous with a raised dark metallic spot in the cell, a series of small black dots covered with golden scales. Female is paler with all metallic spots. Hindwings are whitish to dirty cream. Young larvae are greyish-white, with a distinctive dark-brown to black head and prothoracic shield. Fully grown final-instar larvae are 21- 25 mm long, creamy-white with five purplish-brown stripes (3 dorsal and 2 lateral) along the body. It is similar to C. auricilius. Biology: Eggs are flat scale like and are laid in clusters overlapping each other on the lower or upper leaf surface in longitudinal overlapping rows, each cluster containing up to 80 eggs. Fecundity is around 488 eggs. Ovipositional period is 3 days. Egg period is 6 days in Kerala. Larvae feed for 23-36 days and there are 6 instars. Pupal period is 4 days. It pupates in the larval tunnel. No dormancy or diapause has been reported. Host plants: Maize and sugarcane are the cultivated hosts apart from 33 other species being reported as alternate hosts.
Striped stem borer (SSB), Chilo suppressalis (Walker)
Distribution: This borer species has been reported from plains of India, Assam, West Bengal, Bihar, Orissa and Kerala. Description: There is large amount of variation in the adult morphology of this species. In general, the adults are dirty white to yellow-brown, variably sprinkled with grey-brown scales; Hind wing white to yellow brownish. The head and thorax of male are brown and abdomen is pale in colour. Larvae are dull yellow coloured with ochreous head and prothoracic shield. They have 5 distinct stripes (one median, two sub dorsal and two lateral) and 2 distinct sub lateral stripes, on abdomen. Biology: No information on biology in India is available. However it has been reported from many temperate regions like Japan and China where it is a major pest (Heinrichs, 1994). Female moth may lay 100-550 eggs in batches of 50-80. Eggs are naked and scale like, pale to dark yellow, laid in masses formed of overlapping rows on leaf sheaths. The larvae live gregariously during the first three instars. Larval period is 20-48 days over 5-6 larval instars.
Host Plants: Chilo suppressalis is mainly a pest of rice, but it has been recorded feeding on maize, Scirpus gressus and Panicum crusgalli. Other hosts include sorghum, Panicum miliaceum, Echinochloa spp., Phragmites communis, Saccharum sp., Typha latifolia, water oats (Zizania latifolia, Z. caduciflora and Zizania aquatic).
1. White stem borer (WSB)There is no clarity regarding the taxonomic identity of the white stem borer species reported on rice in India. Two species reported in the literature relevant to rice are described below: a. White rice borer, Scirpophaga nivella (Fabricius)Distribution: White stem borer has been reported as rice pest from Kerala, Tamil Nadu, Orissa and Punjab. Description: Wing span 14-40 mm; fore- and hind wings white with upper side of forewing sometimes yellow brown. Anal tufts are ochreous yellow in female. Biology: The biology of this species has been studied only in the laboratory (Kamani and Vyas, 1985). The durations for different stages of the life cycle reported are 7.97 days for egg stage, 2.13, 4.63, 5.23, 5.85 and 6.42 days for the first, second, third, fourth and fifth larval instars respectively. The pre pupal and pupal periods reported are 1.45 and 11.80 days respectively. The life span of male adult is 3.63 days while that of female is 3.44 days. Host plants: Cyperus spp, Saccharum officinarum, S. spontaneurn, S.arundinaceum, Eleocharis sp, Cyanodon dactylon and Oryza australiensis have been reported as alternate hosts of this insect in India. b. White stem borer, Scirpophaga innotata (Walker) Description: The moth resembles YSB, but is white in colour without black spot on forewing. The upper side of forewing is pale ochreous or white in both sexes, without any markings; Labial palpi is about twice the diameter of eye. Hind wings are with the frenulum spine double in female. Anal tufts whitish in female. Hind wings are white in colour. The larva is also similar to that of YSB but white in colour. S. innotata is a monophagous pest. Biology: All information on biology of S. innotata is from Indonesia. Eggs are laid in clusters of 70-260, usually on the underside of young leaves and covered with a tuft of hairs. Incubation period is 4-9 days. The young larva penetrates th
Yellow stem borer (YSB), Scirpophaga incertulas (Walker) Distribution: This species is prevalent in many states across the country. It is a serious pest in all the rice ecosystems, particularly in deep water rices. Description: The forewing of the female YSB moth is ochreous yellow to whitish with a black spot in the middle. It has a wingspan of 24-36 mm. Its abdomen is wide anal tufts are pale ochreous. The adult male is smaller than female. The forewings are gray or light brown in color and have two rows of black spots at the tip. Sometimes the males are whitish yellow and spots on the forewing are not very clear. Variation in the intensity of colour in the forewing and the size of the moth has also been observed. Biology: Adults mate only once and up to 150 eggs are laid per female. Each female lays 1 -3 egg masses. Egg masses are usually laid on leaf tips but they are also laid on the base of the stems. The size of the egg mass also varies with the brood. The egg mass of YSB is covered with pale ochreous (buff coloured) hairs from the anal tufts of the female. Individual eggs are white, oval and flattened. Egg period varies from 5-9 days and the newly hatched larvae disperse through silken threads and bore into the plant. The first instar YSB larva is about 1.5 mm long. A full-grown larva is pale yellow to yellowish green with brown head and prothoracic shield and measures 20 mm. It feeds within the plant for more than 30 days and undergoes 5 -7 moults. Usually only one larva is found in a tiller. The number of moults and larval duration depends on the prevailing temperature. Larval diapause is a common phenomenon. The YSB pupa is whitish to pale yellowish green and measures about 12 mm long. It is enclosed in a white silk cocoon. Fresh cocoon is pale brown and turns dark brown with age. The pupal period ranges from 6-10 days Host plants: Though considered predominantly as a monophagous pest, YSB has also been reported from w
The spread of rice tungro disease can be checked indirectly by controlling the vector by suitable pesticide application. As the plants are more vulnerable to RTV infection during early stages of growth, chemical protection of the nursery effectively reduces green leafhopper population and thereby minimises the build up of virus inoculum as well as the pace of transmission.
Nursery protection is the key to successful managementof RTV. Incorporate carbofuran 3 G @ 30 to 35 kg I ha or p ho rate 10 G @ 12 to 15 kg I ha of nursery in top 2-5 cm layer of the soil before sowing sprouted seeds. If such incorporation is not possible, broadcast the recommended insecticides 4 to 5 days after sowing in a thin film of water and allow this water to seep completely. A further foliar spray application of monocrotophos 36 EC (@ 1.0 I I ha) or carbaryl 50 WP (@ 2.0 kg I ha) or phosphamidon 85 WSC (@ 0.65 11 ha) should be given around 15th and 25th day after sowing, depending on green leafhopper population. Do not use the same insecticides for repeated applications as a long term pest management strategy.
Protection in later crop growth stages
Usually gall midge and stem borer also appear in the field along with green leafhoppers as a complex. For such situations, carbofuran 3 G (@ 25 kg I ha) orphorate 10 G (@ 7.5 kg I ha) may be applied 10 days after planting. Depending on the further need and intensity of disease occurrence, recommended plant protection measures already indicated may be adopted.
Tungro virus can not be directly controlled by applying any chemical. The best method of preventing tungro is to grow resistant varieties. A variety may be resistant to virus or the insect vector or to both virus and insect vector. VIKRAMARYA
, developed at Directorate of Rice Research, Hyderabad is the resistant variety now available for general cultivation. Other promising resistant medium duration cultures include: IET 9994, IET 8560 and IET 8565 with slender grains and IET 8902 with long bold grains.
When young (nymphs) and adult green leafhoppers feed on diseased plants, virus particles get attached to mouth parts (stylets). As these insects fly and feed on other plants, the virus particles from the stylets get introduced into healthy plants. The insects pick up virus particles within 5 minutes of feeding and can transmit these particles to other healthy plants. The green leafhoppers can not retain virus for a long time. They acquire virus again through repeated feedings. Generally, 8 -10 days after such an introduction of virus in plants, tungro virus disease symptoms appear.
Vector Transmission of RTV
Tungro virus disease is caused by two kinds of virus particles namely, BACILLIFORM (rod shaped) and SPHERICAL (round). Plants with only bacilliform virus particles show mild discolouration, reduced tillering and stunting. But, the green leafhoppers can not transmit RTV from these plants to others.
Plants possessing only spherical particles do not show any disease symptoms but serve as a source of infection. Green leafhoppers can transmit spherical particles to other plants.
Plants having both, bacilliform and spherical particles together, express severe symptoms of the disease and is the most destructive combination. Green leafhoppers pick and transmit both the particles